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Ishizaki T.,Japan International Research Center for Agricultural science | Ishizaki T.,Tropical Agriculture Research Front | Kumashiro T.,Japan International Research Center for Agricultural science
In Vitro Cellular and Developmental Biology - Plant | Year: 2011

In the use of genetic transformation in breeding, there are several possible problems including multiple copy insertion of transgene, sterility caused by somaclonal variation and gene silencing. In this study, we characterized transgenic New Rice for Africa (NERICA) produced by Agrobacterium-mediated methods with respect to copy number of transgene, fertility, and expression level of an introduced GUS gene. Southern blot analysis of primary transformants demonstrated that about half of the events carried a single copy of the transgene regardless of the cell density of Agrobacerium for inoculation. We examined ten procedures, consisting of different time periods and times of subculture for callus formation and the starting times of hygromycin-based selection of transformed cells, for transformation of NERICA cultivars to produce transformants within a short culture period at high frequency. A new culture method developed in this study required only about 1.5 mo from the beginning of tissue culture to transformants, whereas a standard protocol we developed previously needed about 2 mo of culture; however, it did not significantly reduce percentages of sterile plants. Fertile T0 plants produced fertile T1 plants at higher frequency. However, fertility was not inherited in a simple fashion: both fertile and partially sterile T0 plants produced fertile, partially sterile and sterile T1 plants. Expression assay of an introduced GUS gene revealed position effects in seven independent homozygous transformed lines carrying one copy of the transgene. Points to pay attention to in the use of genetic transformation in breeding are discussed. © 2011 The Society for In Vitro Biology. Source

Ichinose K.,Tropical Agriculture Research Front | Hoa N.V.,Southern Research Institute | Bang D.V.,Southern Research Institute | Tuan D.H.,Southern Research Institute | Dien L.Q.,Southern Research Institute
Crop Protection | Year: 2012

No sustainable management practices have been established yet for citrus greening disease (CG). Here we show the efficacy of interplanting guava on CG and its limitation. In 2004, four farmers in southern Vietnam found fewer occurrences of CG in their orchards with guava interplanting than in other orchards without it. The efficacy of guava interplanting was evaluated from field assessment in 93 citrus orchards in southern Vietnam. The CG infection was lowest in orchards where either chemical control with both non-neonicotinoid insecticides and neonicotinoids or the interplanting with guava was performed. Three field experiments were then carried out investigating guava interplanting. In these experiments, no citrus trees in orchards interplanted with guavas were infected by CG for over one year and a few months, while about 20% of trees were infected during the same period in orchards without guavas. There were significantly fewer psyllids in guava interplanted orchards in the first year, but the insect increased thereafter. Almost all trees were infected by CG after two and a half years irrespective of the presence of guavas, indicating that guava interplanting was effective for one year at most. Guava interplanting reduced invasion by the vector but failed to regulate its subsequent generation succession. © 2011 Elsevier Ltd. Source

Takano S.-I.,Kyushu University | Takasu K.,Kyushu University | Fushimi T.,Tropical Agriculture Research Front | Ichiki R.T.,Kyushu University | And 2 more authors.
Entomological Science | Year: 2012

The coconut hispine beetle Brontispa longissima has been causing serious damage to the coconut palm Cocos nucifera in the Pacific, and Southeast and East Asia. This beetle also attacks Satakentia liukiuensis, an endemic palm on Ishigaki and Iriomote Islands, Japan. To assess the potential impact of B.longissima on S.liukiuensis, we examined the development period, survival rate, egg production and body size of B.longissima on S.liukiuensis at 22-31°C and consumption of S.liukiuensis leaf at 28°C. We also examined these life history traits on C.nucifera at 28°C to compare with those on S.liukiuensis. Brontispa longissima completed their development and reproduced on S.liukiuensis at 22-30°C. Linear regression analysis was used to estimate the effective cumulative temperature (k) as 891.2 degree-days, and the lower developmental threshold as 13.3°C. On the basis of these values and monthly average temperatures on Ishigaki Island, it was estimated that B.longissima has four generations per year on the island. Satakentia liukiuensis was less suitable for B.longissima than C.nucifera in terms of immature survival, development time, resultant adult size and reproduction. The low quality of S.liukiuensis as a host-plant may prevent the outbreak of B.longissima, which has not occurred yet on Ishigaki and Iriomote Islands. © 2012 The Entomological Society of Japan. Source

Kobori Y.,Tropical Agriculture Research Front | Okabe K.,Japan Forestry and Forest Products Research Institute | Kanzaki N.,Japan Forestry and Forest Products Research Institute
Nematology | Year: 2015

An undescribed Bursaphelenchus species was isolated and cultured from Dorcus titanus sakishimanus collected during a field survey of the insect-Associated nematodes in subtropical Japan. The stag beetles were collected from Ishigaki Island, Okinawa, Japan, and dissected to examine their nematode associates. Then the dissected bodies were individually transferred to 2.0% agar plates, and nematode propagation on the plates was periodically examined. Nematodes were first recovered from the agar plate, i.e., the number of nematodes carried by the beetle was low, and infection was not confirmed during dissection. The new species was morphologically and phylogenetically (on a molecular basis) close to B. gerberae, which was isolated from the palm weevil, Rhynchophorus palmarum (Curculionidae), from tropical America, and to other weevil-Associated Bursaphelenchus species. However, the new species can be distinguished from its close relatives by its typological characters, e.g., long and slender female tail and male spicule morphology as well as phylogenetic status inferred from the near-full-length of the small subunit (SSU) of the ribosomal RNA gene. The new species is described and illustrated herein as B. sakishimanus n. sp. and its molecular profiles, near-full-length SSU, and D2-D3 expansion segments of the large subunit of ribosomal RNA are described. This is the second Bursaphelenchus species associated with stag beetles (Lucanidae). © 2015 Koninklijke Brill NV, Leiden. Source

Anugroho F.,Kagoshima University | Kitou M.,University of Ryukyus | Nagumo F.,Tropical Agriculture Research Front | Kinjo K.,University of Ryukyus | Jayasinghe G.Y.,Kagoshima University
Soil Science and Plant Nutrition | Year: 2010

Soil acidity is one of the most serious causes of land degradation and limits crop production in subtropical agriculture. A number of legumes have adapted to P-limiting conditions, and the aim of the present study was to select an appropriate species for use as a winter legume cover crop under subtropical soil conditions in Okinawa, where P deficiency stems from soil acidification. Four vetch and four clover species were examined in pot trials. Of these, hairy vetch (Vicia villosa Roth) was found to be the most tolerant of P-limiting conditions. The shoot biomass of hairy vetch was also generally higher than that in the clover species when the P supply was non-limiting in the spring season. Hairy vetch was then compared in a pot trial with four clover species for an extended period of growth with adequate P supply. The N fixing activity of hairy vetch in the vegetative stage was 3.2-fold greater than that of the clover species. Nitrogen and P uptake in shoots and roots was significantly higher in hairy vetch than in the clover species in the vegetative and flowering stages. The C/N ratio in the shoots and roots of hairy vetch tended to be lower than that in the clover species. Shoot K uptake by hairy vetch was significantly higher in the vegetative stage than that in the clover species. In a field trial, shoot biomass and nutrient uptake of hairy vetch were similar on four different subtropical soils with pH values ranging from 5.7 to 7.5. Hairy vetch is an appropriate winter legume cover crop to improve subtropical soils by increasing organic matter and supplying nutrients to the subsequent crop. © 2010 Japanese Society of Soil Science and Plant Nutrition. Source

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